___ it wasn't so cold,I'd like to go swimming.要语法的!答案好象是Because

If
虚拟语气
例如，
If I were you, I will talk with her.
因为我不可能是你，所以不是现实，所以是虚拟语气。
Should you had been there, you would be very happy.
因为已经过去，你不可能去了，所以是虚拟语气。

If 虚拟语气的用法
如果不太冷，我想去游泳
If I were to go, I would be late.
倘若我去，就要迟到
If that is true, what should we do?
假设那是真的我们该怎么办呢?

If 是正确的。
如果不这么冷，我很想去游泳。
整句是虚拟语气。

If
如果天气不是很冷，我就去游泳。
If it is going to rain, I'd like to stay at home.
If ... I'd like to....如果 ...我就...

Because it wasn't so cold,I'd like to go swimming.因为天气不是很冷,所以我想去游泳.不好意思看错wasn't为was了.表示因果关系的句子,但英文不同中文的因为所以一齐出现,在英语中,用了因为Because 就不必用所以so....